There are numerous bone fixation/fusion systems, devices and associated methods for stabilizing adjacent bone segments, thereby enhancing the healing of fractures and/or promoting union of joints being fused together. Adjacent bone segments may include parts of the same bone that have been fractured, or two or more individual bones separated by a space or joint. Examples of orthopedic fixation/fusion devices include bone screws, metal pins, intramedullary implants, and compressive implants. A compressive implant may include a body inserted into a first and a second bone segment spanning the fracture line or joint between the two bones, with one end anchored to an interior region of the second bone segment, while the other end is anchored to a location outside of the first bone. The two anchors are used to place the body in compression which in turn compresses and fixes the bone segments relative to the fracture line or joint.
As stated, bone fixation/fusion systems, with the exception of cable-type orthopedic implants, which cannot provide rotational stabilization, are generally anchored to the cancellous bone material in the interior of the bone. This material is soft and spongy and has inferior holding capability when compared to the exterior, cortical bone portions. The forces imposed on such devices may exceed the holding capability of the cancellous bone, and may result in implant failure.